I moved a static HTML file to src/views, and then saw the following error:
Error: Failed to lookup view “checkout” in views directory “/app/src/views”
The error turned out to be a trailing space I accidentally typed when moving the file through the “rename” UI. The only indications that something was amiss in the UI were a different color for the file extension and lack of syntax highlighting. Trailing whitespace in filenames should be trimmed.